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Composite Operational Excellence Score (0-100) — average percentile rank across 7 dimensions in three sub-scores: Reliability (capacity factor, forced outage days, B2B avg streak), Efficiency (fuel utilization, refuel duration), and Discipline (startup duration, scram count). 5-year window. Higher = more operationally excellent. Click to see the full breakdown.
25
Excellence
#86 of 94 ↑2
Bottom Quartile
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Days of continuous operation since the last outage ended. Has forced outage(s) since last refueling.
3
Current Run
days
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Longest recorded period of continuous operation between outages (2024-05-09 to 2026-03-23).
683
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold (608 days for this 24-month cycle unit) with no trips to 0% power.
1
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
83.6%
Capacity Factor
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Total number of scheduled refueling outages detected in the historical data.
17
Outages
since 1999
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Average time from first power generation (>0%) to sustained full power (≥95% for 2+ days) across the last 3 scheduled outages. Click to compare against the fleet on the Operator Efficiency Leaderboard.
9.7
Avg Startup
days (last 3)
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Average fuel utilization — percent of the designed fuel cycle that this unit consumes before refueling, derived from the historical burn-down trajectory. Higher = more efficient operator (refuels with less margin remaining; closer to coastdown). Computed as 100% minus the unit's average refuel-point fuel %, using the last 3 years where available, otherwise lifetime average. Click to compare against the fleet on the Operator Efficiency Leaderboard.
98.9%
Fuel Utilization
3yr avg
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NukeWorker's Operational Excellence Score is a composite 0–100 ranking of every active US nuclear unit across 7 publicly observable performance metrics, grouped into three sub-scores:
• Reliability — capacity factor, forced outage days, B2B avg streak
• Efficiency — fuel utilization, refuel duration
• Discipline — startup duration, scram count
Each unit's metric is converted to a percentile across the active fleet. Sub-score = average of its components; composite = average of the three sub-scores. Use the time-window toggle below to switch between 3yr / 5yr / lifetime.
• Reliability — capacity factor, forced outage days, B2B avg streak
• Efficiency — fuel utilization, refuel duration
• Discipline — startup duration, scram count
Each unit's metric is converted to a percentile across the active fleet. Sub-score = average of its components; composite = average of the three sub-scores. Use the time-window toggle below to switch between 3yr / 5yr / lifetime.
Time window
— change how far back we look
NukeWorker's
Operational
Excellence Score
Operational
Excellence Score
25/100
Bottom Quartile · #86/94
5-year window
Fermi 2 ranks #86 of 94 active US units on NukeWorker's Operational Excellence Score over the 5-year window. Strongest area: B2B Avg Streak (75th percentile). Weakest: Refuel Duration (7th percentile).
Reliability
39
Capacity factor + Forced outages + B2B streaks
Efficiency
13
Fuel utilization + Refuel duration
Discipline
24
Startup duration + Scram count
Cohort Rankings
apples-to-apples comparison within each peer group
Reactor type:
#27 of 31
BWR
Containment:
#18 of 19
Mark I (BWR)
Cycle length:
#36 of 40
24-month cycle
Fleet rank above (86 of 94) compares all active US units; cohort ranks compare only against units sharing this property.
Per-dimension breakdown (7 metrics)
Capacity Factor
12th
82.5% (higher better, Reliability)
Forced Outage Days/yr
30th
6.4d (lower better, Reliability)
B2B Avg Streak
75th
682d (higher better, Reliability)
Fuel Utilization
18th
95.8% (higher better, Efficiency)
Refuel Duration
7th
49d (lower better, Efficiency)
Startup Duration
19th
6.7d (lower better, Discipline)
Scrams (5-year)
30th
0.6/yr (lower better, Discipline)
Each dimension's percentile is computed across the active US fleet (94 units with sufficient history). Sub-score = average of its component percentiles. Composite = average of the three sub-scores. 5-year window. View full leaderboard →
Methodology
NukeWorker's Operational Excellence Score is a composite ranking that combines 7 publicly observable performance metrics into a single 0-100 number per US nuclear unit.
How it's computed: Each unit's raw value is converted to a percentile (0-100) within the 94 active US units that have at least 2 completed refueling cycles. The 7 percentiles are averaged into 3 sub-scores (Reliability, Efficiency, Discipline), and those are averaged into the final composite.
Active window — 5-year:
- Reliability — Capacity factor (5yr), forced outage days/yr (5yr), B2B avg streak (lifetime)
- Efficiency — in-cycle fuel utilization (3yr), median refuel duration (5yr)
- Discipline — robust mean startup duration, scrams/yr (5yr, annualised)
Cohort rankings: alongside the fleet rank, each unit gets ranked within its reactor type (PWR/BWR), containment design (Ice Condenser, Mark I, etc.), and cycle length (12/18/24-month). Useful for apples-to-apples comparisons.
What's excluded: subjective community ratings, confidential INPO ratings, financial metrics. We only use publicly available NRC + cycle data.
Why three windows? 5yr (default) is the industry standard. 3yr captures recent operational changes and post-pandemic recovery. Lifetime gives newer units a fair comparison and reveals long-term consistency.
Edge cases: units with fewer than 2 cycles (e.g., Vogtle 4) show "Provisional". Decommissioned units excluded.
Refresh cadence: recomputed daily. Each window cached separately.
A data-derived proxy for operational performance; not affiliated with INPO. INPO ratings are confidential and qualitative — ours is public and quantitative.
5-yr trend:
↑ +6.7 pts vs 2025
Compare Fermi 2 head-to-head with up to 3 other units.
Compare now
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Duration of each outage in days, shown chronologically. Green bars are scheduled refueling outages, red bars are forced/unscheduled. The orange dashed line marks the average duration. Extended outages (>180 days) and D&D periods are excluded.
Outage Duration Trend
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Days between consecutive scheduled refueling outage starts, showing operating cycle regularity. The purple dashed line marks the average cycle length. Most U.S. reactors operate on 18-month (547 day) or 24-month (730 day) cycles.
Cycle Length History
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Time in days from first power generation (>0%) to sustained full power (≥95% for 2+ consecutive days) after each scheduled refueling outage. The dashed line marks the average. Includes startup testing holds and power dips.
Startup Duration Trend
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Monthly capacity factor with outage events overlaid as red bands. Green bars show average power level per month. Toggle to Daily view for raw daily data.
Power History
| Type ⇅ | Actual Start ⇅ | Actual End ⇅ | Duration ⇅ | Days Online ⇅ | Scheduled | Delta |
|---|---|---|---|---|---|---|
|
Scheduled
|
2026-03-23 | 2026-05-11 | 50 | 683d | 2026-03-21 | +2d |
|
Scheduled
|
2024-03-23 | 2024-05-09 | 48 | 62d | 2024-03-22 | +1d |
|
Unscheduled
|
2024-01-19 | 2024-01-21 | 3 | 134d | - | - |
|
Unscheduled
|
2023-08-21 | 2023-09-07 | 18 | 421d | - | - |
|
Scram
# 55964
|
2022-06-25 | 2022-06-26 | 2 | 48d | - | - |
|
Scheduled
SGR/Major
|
2022-02-05 | 2022-05-08 | 93 | 259d | 2022-02-05 | 0d |
|
Unscheduled
|
2021-05-17 | 2021-05-22 | 6 | 292d | - | - |
|
Scheduled
SGR/Major
|
2020-03-21 | 2020-07-29 | 131 | 446d | 2020-03-21 | 0d |
|
Unscheduled
|
2018-12-07 | 2018-12-31 | 25 | 43d | - | - |
|
Scheduled
|
2018-09-22 | 2018-10-25 | 34 | 139d | 2018-09-22 | 0d |
|
Scram
# 53336
|
2018-04-15 | 2018-05-06 | 22 | 362d | - | - |
|
Scheduled
|
2017-03-18 | 2017-04-18 | 32 | 127d | 2017-03-18 | 0d |
|
Unscheduled
|
2016-11-07 | 2016-11-11 | 5 | 179d | - | - |
|
Unscheduled
|
2016-05-04 | 2016-05-12 | 9 | 161d | - | - |
|
Scheduled
|
2015-09-14 | 2015-11-25 | 73 | 164d | 2015-09-28 | -14d |
|
Scram
# 50903
|
2015-03-20 | 2015-04-03 | 15 | 333d | - | - |
|
Unscheduled
|
2014-04-16 | 2014-04-21 | 6 | 19d | - | - |
|
Scheduled
|
2014-02-11 | 2014-03-28 | 46 | 143d | 2014-02-10 | +1d |
|
Unscheduled
|
2013-09-09 | 2013-09-21 | 13 | 123d | - | - |
|
Unscheduled
|
2013-04-27 | 2013-05-09 | 13 | 118d | - | - |
|
Scram
# 48487
|
2012-11-08 | 2012-12-30 | 53 | 51d | - | - |
|
Scram
# 48309
|
2012-09-15 | 2012-09-18 | 4 | 50d | - | - |
|
Unscheduled
|
2012-07-24 | 2012-07-27 | 4 | 2d | - | - |
|
Scram
# 48047
|
2012-06-26 | 2012-07-22 | 27 | 55d | - | - |
|
Scheduled
|
2012-03-26 | 2012-05-02 | 38 | 407d | 2012-03-26 | 0d |
|
Unscheduled
|
2011-02-12 | 2011-02-13 | 2 | 2d | - | - |
|
Unscheduled
|
2011-01-29 | 2011-02-10 | 13 | 59d | - | - |
|
Scheduled
|
2010-10-25 | 2010-12-01 | 38 | 133d | 2010-10-23 | +2d |
|
Unscheduled
|
2010-06-06 | 2010-06-14 | 9 | 71d | - | - |
|
Unscheduled
|
2010-03-26 | 2010-03-27 | 2 | 135d | - | - |
|
Unscheduled
|
2009-10-01 | 2009-11-11 | 42 | 109d | - | - |
|
Unscheduled
|
2009-06-13 | 2009-06-14 | 2 | 45d | - | - |
|
Scheduled
|
2009-03-28 | 2009-04-29 | 33 | 420d | 2009-03-28 | 0d |
|
Unscheduled
|
2008-02-01 | 2008-02-02 | 2 | 77d | - | - |
|
Unscheduled
|
2007-11-15 | 2007-11-16 | 2 | 2d | - | - |
|
Scheduled
|
2007-09-29 | 2007-11-13 | 46 | 425d | 2007-09-29 | 0d |
|
Unscheduled
|
2006-07-30 | 2006-07-31 | 2 | 11d | - | - |
|
Unscheduled
|
2006-07-09 | 2006-07-19 | 11 | 22d | - | - |
|
Unscheduled
|
2006-06-16 | 2006-06-17 | 2 | 19d | - | - |
|
Unscheduled
|
2006-05-20 | 2006-05-28 | 9 | 16d | - | - |
|
Scheduled
|
2006-03-26 | 2006-05-04 | 40 | 255d | 2006-03-25 | +1d |
|
Unscheduled
|
2005-06-26 | 2005-07-14 | 19 | 141d | - | - |
|
Unscheduled
|
2005-01-25 | 2005-02-05 | 12 | 51d | - | - |
|
Unscheduled
Startup Hold
|
2004-12-05 | 2004-12-05 | 1 | 4d | - | - |
|
Scheduled
|
2004-11-06 | 2004-12-01 | 26 | 62d | 2004-11-05 | +1d |
|
Unscheduled
|
2004-09-04 | 2004-09-05 | 2 | 18d | - | - |
|
Unscheduled
|
2004-08-10 | 2004-08-17 | 8 | 336d | - | - |
|
Unscheduled
|
2003-09-06 | 2003-09-09 | 4 | 19d | - | - |
|
Unscheduled
|
2003-08-15 | 2003-08-18 | 4 | 100d | - | - |
|
Scheduled
|
2003-03-29 | 2003-05-07 | 40 | 87d | 2003-03-29 | 0d |
|
Unscheduled
|
2002-12-29 | 2003-01-01 | 4 | 86d | - | - |
|
Unscheduled
|
2002-10-03 | 2002-10-04 | 2 | 300d | - | - |
|
Unscheduled
|
2001-12-06 | 2001-12-07 | 2 | 10d | - | - |
|
Scheduled
|
2001-10-29 | 2001-11-26 | 29 | 183d | 2001-10-29 | 0d |
|
Unscheduled
|
2001-04-28 | 2001-04-29 | 2 | 344d | - | - |
|
Scheduled
|
2000-04-02 | 2000-05-19 | 48 | 318d | 2000-04-02 | 0d |
|
Unscheduled
|
1999-05-19 | 1999-05-20 | 2 | - | - | - |
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